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-rw-r--r--lib/CodeGen/AggressiveAntiDepBreaker.cpp241
1 files changed, 134 insertions, 107 deletions
diff --git a/lib/CodeGen/AggressiveAntiDepBreaker.cpp b/lib/CodeGen/AggressiveAntiDepBreaker.cpp
index c37c793b56d0..8e3f8e770486 100644
--- a/lib/CodeGen/AggressiveAntiDepBreaker.cpp
+++ b/lib/CodeGen/AggressiveAntiDepBreaker.cpp
@@ -28,10 +28,15 @@
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
+// If DebugDiv > 0 then only break antidep with (ID % DebugDiv) == DebugMod
static cl::opt<int>
-AntiDepTrials("agg-antidep-trials",
- cl::desc("Maximum number of anti-dependency breaking passes"),
- cl::init(1), cl::Hidden);
+DebugDiv("agg-antidep-debugdiv",
+ cl::desc("Debug control for aggressive anti-dep breaker"),
+ cl::init(0), cl::Hidden);
+static cl::opt<int>
+DebugMod("agg-antidep-debugmod",
+ cl::desc("Debug control for aggressive anti-dep breaker"),
+ cl::init(0), cl::Hidden);
AggressiveAntiDepState::AggressiveAntiDepState(MachineBasicBlock *BB) :
GroupNodes(TargetRegisterInfo::FirstVirtualRegister, 0) {
@@ -108,7 +113,7 @@ AggressiveAntiDepBreaker(MachineFunction& MFi,
MRI(MF.getRegInfo()),
TRI(MF.getTarget().getRegisterInfo()),
AllocatableSet(TRI->getAllocatableSet(MF)),
- State(NULL), SavedState(NULL) {
+ State(NULL) {
/* Collect a bitset of all registers that are only broken if they
are on the critical path. */
for (unsigned i = 0, e = CriticalPathRCs.size(); i < e; ++i) {
@@ -128,13 +133,6 @@ AggressiveAntiDepBreaker(MachineFunction& MFi,
AggressiveAntiDepBreaker::~AggressiveAntiDepBreaker() {
delete State;
- delete SavedState;
-}
-
-unsigned AggressiveAntiDepBreaker::GetMaxTrials() {
- if (AntiDepTrials <= 0)
- return 1;
- return AntiDepTrials;
}
void AggressiveAntiDepBreaker::StartBlock(MachineBasicBlock *BB) {
@@ -206,8 +204,6 @@ void AggressiveAntiDepBreaker::StartBlock(MachineBasicBlock *BB) {
void AggressiveAntiDepBreaker::FinishBlock() {
delete State;
State = NULL;
- delete SavedState;
- SavedState = NULL;
}
void AggressiveAntiDepBreaker::Observe(MachineInstr *MI, unsigned Count,
@@ -241,10 +237,6 @@ void AggressiveAntiDepBreaker::Observe(MachineInstr *MI, unsigned Count,
}
}
DEBUG(errs() << '\n');
-
- // We're starting a new schedule region so forget any saved state.
- delete SavedState;
- SavedState = NULL;
}
bool AggressiveAntiDepBreaker::IsImplicitDefUse(MachineInstr *MI,
@@ -283,27 +275,20 @@ void AggressiveAntiDepBreaker::GetPassthruRegs(MachineInstr *MI,
}
}
-/// AntiDepEdges - Return in Edges the anti- and output-
-/// dependencies on Regs in SU that we want to consider for breaking.
-static void AntiDepEdges(SUnit *SU,
- const AntiDepBreaker::AntiDepRegVector& Regs,
- std::vector<SDep*>& Edges) {
- AntiDepBreaker::AntiDepRegSet RegSet;
- for (unsigned i = 0, e = Regs.size(); i < e; ++i)
- RegSet.insert(Regs[i]);
-
+/// AntiDepEdges - Return in Edges the anti- and output- dependencies
+/// in SU that we want to consider for breaking.
+static void AntiDepEdges(SUnit *SU, std::vector<SDep*>& Edges) {
+ SmallSet<unsigned, 4> RegSet;
for (SUnit::pred_iterator P = SU->Preds.begin(), PE = SU->Preds.end();
P != PE; ++P) {
if ((P->getKind() == SDep::Anti) || (P->getKind() == SDep::Output)) {
unsigned Reg = P->getReg();
- if (RegSet.count(Reg) != 0) {
+ if (RegSet.count(Reg) == 0) {
Edges.push_back(&*P);
- RegSet.erase(Reg);
+ RegSet.insert(Reg);
}
}
}
-
- assert(RegSet.empty() && "Expected all antidep registers to be found");
}
/// CriticalPathStep - Return the next SUnit after SU on the bottom-up
@@ -332,7 +317,8 @@ static SUnit *CriticalPathStep(SUnit *SU) {
}
void AggressiveAntiDepBreaker::HandleLastUse(unsigned Reg, unsigned KillIdx,
- const char *tag) {
+ const char *tag, const char *header,
+ const char *footer) {
unsigned *KillIndices = State->GetKillIndices();
unsigned *DefIndices = State->GetDefIndices();
std::multimap<unsigned, AggressiveAntiDepState::RegisterReference>&
@@ -343,6 +329,8 @@ void AggressiveAntiDepBreaker::HandleLastUse(unsigned Reg, unsigned KillIdx,
DefIndices[Reg] = ~0u;
RegRefs.erase(Reg);
State->LeaveGroup(Reg);
+ DEBUG(if (header != NULL) {
+ errs() << header << TRI->getName(Reg); header = NULL; });
DEBUG(errs() << "->g" << State->GetGroup(Reg) << tag);
}
// Repeat for subregisters.
@@ -354,10 +342,14 @@ void AggressiveAntiDepBreaker::HandleLastUse(unsigned Reg, unsigned KillIdx,
DefIndices[SubregReg] = ~0u;
RegRefs.erase(SubregReg);
State->LeaveGroup(SubregReg);
+ DEBUG(if (header != NULL) {
+ errs() << header << TRI->getName(Reg); header = NULL; });
DEBUG(errs() << " " << TRI->getName(SubregReg) << "->g" <<
State->GetGroup(SubregReg) << tag);
}
}
+
+ DEBUG(if ((header == NULL) && (footer != NULL)) errs() << footer);
}
void AggressiveAntiDepBreaker::PrescanInstruction(MachineInstr *MI, unsigned Count,
@@ -377,9 +369,7 @@ void AggressiveAntiDepBreaker::PrescanInstruction(MachineInstr *MI, unsigned Cou
unsigned Reg = MO.getReg();
if (Reg == 0) continue;
- DEBUG(errs() << "\tDead Def: " << TRI->getName(Reg));
- HandleLastUse(Reg, Count + 1, "");
- DEBUG(errs() << '\n');
+ HandleLastUse(Reg, Count + 1, "", "\tDead Def: ", "\n");
}
DEBUG(errs() << "\tDef Groups:");
@@ -427,15 +417,17 @@ void AggressiveAntiDepBreaker::PrescanInstruction(MachineInstr *MI, unsigned Cou
if (!MO.isReg() || !MO.isDef()) continue;
unsigned Reg = MO.getReg();
if (Reg == 0) continue;
- // Ignore passthru registers for liveness...
- if (PassthruRegs.count(Reg) != 0) continue;
+ // Ignore KILLs and passthru registers for liveness...
+ if ((MI->getOpcode() == TargetInstrInfo::KILL) ||
+ (PassthruRegs.count(Reg) != 0))
+ continue;
- // Update def for Reg and subregs.
+ // Update def for Reg and aliases.
DefIndices[Reg] = Count;
- for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
- *Subreg; ++Subreg) {
- unsigned SubregReg = *Subreg;
- DefIndices[SubregReg] = Count;
+ for (const unsigned *Alias = TRI->getAliasSet(Reg);
+ *Alias; ++Alias) {
+ unsigned AliasReg = *Alias;
+ DefIndices[AliasReg] = Count;
}
}
}
@@ -589,72 +581,108 @@ bool AggressiveAntiDepBreaker::FindSuitableFreeRegisters(
return false;
}
- // FIXME: for now just handle single register in group case...
- if (Regs.size() > 1) {
- DEBUG(errs() << "\tMultiple rename registers in group\n");
- return false;
+#ifndef NDEBUG
+ // If DebugDiv > 0 then only rename (renamecnt % DebugDiv) == DebugMod
+ if (DebugDiv > 0) {
+ static int renamecnt = 0;
+ if (renamecnt++ % DebugDiv != DebugMod)
+ return false;
+
+ errs() << "*** Performing rename " << TRI->getName(SuperReg) <<
+ " for debug ***\n";
}
+#endif
// Check each possible rename register for SuperReg in round-robin
// order. If that register is available, and the corresponding
// registers are available for the other group subregisters, then we
// can use those registers to rename.
- BitVector SuperBV = RenameRegisterMap[SuperReg];
const TargetRegisterClass *SuperRC =
TRI->getPhysicalRegisterRegClass(SuperReg, MVT::Other);
const TargetRegisterClass::iterator RB = SuperRC->allocation_order_begin(MF);
const TargetRegisterClass::iterator RE = SuperRC->allocation_order_end(MF);
if (RB == RE) {
- DEBUG(errs() << "\tEmpty Regclass!!\n");
+ DEBUG(errs() << "\tEmpty Super Regclass!!\n");
return false;
}
+ DEBUG(errs() << "\tFind Registers:");
+
if (RenameOrder.count(SuperRC) == 0)
RenameOrder.insert(RenameOrderType::value_type(SuperRC, RE));
- DEBUG(errs() << "\tFind Register:");
-
const TargetRegisterClass::iterator OrigR = RenameOrder[SuperRC];
const TargetRegisterClass::iterator EndR = ((OrigR == RE) ? RB : OrigR);
TargetRegisterClass::iterator R = OrigR;
do {
if (R == RB) R = RE;
--R;
- const unsigned Reg = *R;
+ const unsigned NewSuperReg = *R;
// Don't replace a register with itself.
- if (Reg == SuperReg) continue;
-
- DEBUG(errs() << " " << TRI->getName(Reg));
+ if (NewSuperReg == SuperReg) continue;
- // If Reg is dead and Reg's most recent def is not before
- // SuperRegs's kill, it's safe to replace SuperReg with Reg. We
- // must also check all subregisters of Reg.
- if (State->IsLive(Reg) || (KillIndices[SuperReg] > DefIndices[Reg])) {
- DEBUG(errs() << "(live)");
- continue;
- } else {
- bool found = false;
- for (const unsigned *Subreg = TRI->getSubRegisters(Reg);
- *Subreg; ++Subreg) {
- unsigned SubregReg = *Subreg;
- if (State->IsLive(SubregReg) || (KillIndices[SuperReg] > DefIndices[SubregReg])) {
- DEBUG(errs() << "(subreg " << TRI->getName(SubregReg) << " live)");
- found = true;
- break;
+ DEBUG(errs() << " [" << TRI->getName(NewSuperReg) << ':');
+ RenameMap.clear();
+
+ // For each referenced group register (which must be a SuperReg or
+ // a subregister of SuperReg), find the corresponding subregister
+ // of NewSuperReg and make sure it is free to be renamed.
+ for (unsigned i = 0, e = Regs.size(); i != e; ++i) {
+ unsigned Reg = Regs[i];
+ unsigned NewReg = 0;
+ if (Reg == SuperReg) {
+ NewReg = NewSuperReg;
+ } else {
+ unsigned NewSubRegIdx = TRI->getSubRegIndex(SuperReg, Reg);
+ if (NewSubRegIdx != 0)
+ NewReg = TRI->getSubReg(NewSuperReg, NewSubRegIdx);
+ }
+
+ DEBUG(errs() << " " << TRI->getName(NewReg));
+
+ // Check if Reg can be renamed to NewReg.
+ BitVector BV = RenameRegisterMap[Reg];
+ if (!BV.test(NewReg)) {
+ DEBUG(errs() << "(no rename)");
+ goto next_super_reg;
+ }
+
+ // If NewReg is dead and NewReg's most recent def is not before
+ // Regs's kill, it's safe to replace Reg with NewReg. We
+ // must also check all aliases of NewReg, because we can't define a
+ // register when any sub or super is already live.
+ if (State->IsLive(NewReg) || (KillIndices[Reg] > DefIndices[NewReg])) {
+ DEBUG(errs() << "(live)");
+ goto next_super_reg;
+ } else {
+ bool found = false;
+ for (const unsigned *Alias = TRI->getAliasSet(NewReg);
+ *Alias; ++Alias) {
+ unsigned AliasReg = *Alias;
+ if (State->IsLive(AliasReg) || (KillIndices[Reg] > DefIndices[AliasReg])) {
+ DEBUG(errs() << "(alias " << TRI->getName(AliasReg) << " live)");
+ found = true;
+ break;
+ }
}
+ if (found)
+ goto next_super_reg;
}
- if (found)
- continue;
+
+ // Record that 'Reg' can be renamed to 'NewReg'.
+ RenameMap.insert(std::pair<unsigned, unsigned>(Reg, NewReg));
}
- if (Reg != 0) {
- DEBUG(errs() << '\n');
- RenameOrder.erase(SuperRC);
- RenameOrder.insert(RenameOrderType::value_type(SuperRC, R));
- RenameMap.insert(std::pair<unsigned, unsigned>(SuperReg, Reg));
- return true;
- }
+ // If we fall-out here, then every register in the group can be
+ // renamed, as recorded in RenameMap.
+ RenameOrder.erase(SuperRC);
+ RenameOrder.insert(RenameOrderType::value_type(SuperRC, R));
+ DEBUG(errs() << "]\n");
+ return true;
+
+ next_super_reg:
+ DEBUG(errs() << ']');
} while (R != EndR);
DEBUG(errs() << '\n');
@@ -668,7 +696,6 @@ bool AggressiveAntiDepBreaker::FindSuitableFreeRegisters(
///
unsigned AggressiveAntiDepBreaker::BreakAntiDependencies(
std::vector<SUnit>& SUnits,
- CandidateMap& Candidates,
MachineBasicBlock::iterator& Begin,
MachineBasicBlock::iterator& End,
unsigned InsertPosIndex) {
@@ -681,16 +708,6 @@ unsigned AggressiveAntiDepBreaker::BreakAntiDependencies(
// so just duck out immediately if the block is empty.
if (SUnits.empty()) return 0;
- // Manage saved state to enable multiple passes...
- if (AntiDepTrials > 1) {
- if (SavedState == NULL) {
- SavedState = new AggressiveAntiDepState(*State);
- } else {
- delete State;
- State = new AggressiveAntiDepState(*SavedState);
- }
- }
-
// For each regclass the next register to use for renaming.
RenameOrderType RenameOrder;
@@ -719,21 +736,14 @@ unsigned AggressiveAntiDepBreaker::BreakAntiDependencies(
CriticalPathMI = CriticalPathSU->getInstr();
}
- // Even if there are no anti-dependencies we still need to go
- // through the instructions to update Def, Kills, etc.
#ifndef NDEBUG
- if (Candidates.empty()) {
- DEBUG(errs() << "\n===== No anti-dependency candidates\n");
- } else {
- DEBUG(errs() << "\n===== Attempting to break " << Candidates.size() <<
- " anti-dependencies\n");
- DEBUG(errs() << "Available regs:");
- for (unsigned Reg = 0; Reg < TRI->getNumRegs(); ++Reg) {
- if (!State->IsLive(Reg))
- DEBUG(errs() << " " << TRI->getName(Reg));
- }
- DEBUG(errs() << '\n');
+ DEBUG(errs() << "\n===== Aggressive anti-dependency breaking\n");
+ DEBUG(errs() << "Available regs:");
+ for (unsigned Reg = 0; Reg < TRI->getNumRegs(); ++Reg) {
+ if (!State->IsLive(Reg))
+ DEBUG(errs() << " " << TRI->getName(Reg));
}
+ DEBUG(errs() << '\n');
#endif
// Attempt to break anti-dependence edges. Walk the instructions
@@ -754,14 +764,11 @@ unsigned AggressiveAntiDepBreaker::BreakAntiDependencies(
// Process the defs in MI...
PrescanInstruction(MI, Count, PassthruRegs);
- // The the dependence edges that represent anti- and output-
+ // The dependence edges that represent anti- and output-
// dependencies that are candidates for breaking.
std::vector<SDep*> Edges;
SUnit *PathSU = MISUnitMap[MI];
- AntiDepBreaker::CandidateMap::iterator
- citer = Candidates.find(PathSU);
- if (citer != Candidates.end())
- AntiDepEdges(PathSU, citer->second, Edges);
+ AntiDepEdges(PathSU, Edges);
// If MI is not on the critical path, then we don't rename
// registers in the CriticalPathSet.
@@ -817,12 +824,32 @@ unsigned AggressiveAntiDepBreaker::BreakAntiDependencies(
// anti-dependency since those edges would prevent such
// units from being scheduled past each other
// regardless.
+ //
+ // Also, if there are dependencies on other SUnits with the
+ // same register as the anti-dependency, don't attempt to
+ // break it.
+ for (SUnit::pred_iterator P = PathSU->Preds.begin(),
+ PE = PathSU->Preds.end(); P != PE; ++P) {
+ if (P->getSUnit() == NextSU ?
+ (P->getKind() != SDep::Anti || P->getReg() != AntiDepReg) :
+ (P->getKind() == SDep::Data && P->getReg() == AntiDepReg)) {
+ AntiDepReg = 0;
+ break;
+ }
+ }
for (SUnit::pred_iterator P = PathSU->Preds.begin(),
PE = PathSU->Preds.end(); P != PE; ++P) {
- if ((P->getSUnit() == NextSU) && (P->getKind() != SDep::Anti)) {
+ if ((P->getSUnit() == NextSU) && (P->getKind() != SDep::Anti) &&
+ (P->getKind() != SDep::Output)) {
DEBUG(errs() << " (real dependency)\n");
AntiDepReg = 0;
break;
+ } else if ((P->getSUnit() != NextSU) &&
+ (P->getKind() == SDep::Data) &&
+ (P->getReg() == AntiDepReg)) {
+ DEBUG(errs() << " (other dependency)\n");
+ AntiDepReg = 0;
+ break;
}
}
generated by cgit v1.2.3 (git 2.25.1) at 2025-11-04 06:41:03 +0000